Memory including a plurality of portions and used for reducing program disturbance and program method thereof

ABSTRACT

A memory includes a first portion, a second portion and a controller. The first portion includes a first word line to a kth word line. The second portion is formed above the first portion and includes a (k+1)th word line to an mth word line. When an xth word line is used to perform a program operation, the controller is used to apply a first voltage to the first word line to an (x−2)th word line, a second voltage to an (x−1)th word line, and a third voltage to an (x+1)th word line. x, k and m are positive integers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT Application No.PCT/CN2020/074580 filed on 2020 Feb. 10, the entire contents of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The disclosure is related to a memory and a program method, and moreparticularly, a memory including a plurality of portions and used forreducing program disturbance and a program method thereof.

2. Description of the Prior Art

In order to increase the capacity of a memory, a memory with athree-dimensional structure has been developed. For example, athree-dimensional stack NAND flash memory can be available presently.

A three-dimensional structure of a memory can include a plurality oflayers so as to store more data on a same area. This structure has beenproved to be effective for increasing capacity of memory.

However, program disturbance will become more significant when thenumber of layers is increased. Program disturbance will lead to a higherfailure rate of programming a memory. In addition, pass voltagedisturbance also occurs when using a memory with a plurality of layers.

Hence, a solution for reducing program disturbance and pass voltagedisturbance when operating a three-dimensional memory is in need in thefield.

SUMMARY OF THE INVENTION

An embodiment provides a memory including a first portion, a secondportion and a controller. The first portion includes a first word lineto a kth word line from bottom to top. The second portion is formedabove the first portion and includes a (k+1)th word line to an mth wordline from bottom to top. The controller is used to apply a first voltageto the first word line to an (x−2)th word line, a second voltage to an(x−1)th word line, and a third voltage to an (x+1)th word line when anxth word line is used to perform a program operation. x, k and m arepositive integers.

An embodiment provides a memory including a first portion, a secondportion and a controller. The first portion includes an (m+1)th wordline to an nth word line from bottom to top. The second portion isformed below the first portion and includes a (k+1)th word line to anmth word line from bottom to top. The controller is used to apply afirst voltage to an (x+2)th word line to the nth word line, a secondvoltage to an (x+1)th word line, a third voltage to an (x−1)th wordline, a fourth voltage to the (m+1)th word line to an (x−2)th word line,and a fifth voltage to the (k+1)th word line to the mth word line whenan xth word line is used to perform a program operation. x, k and m areintegers. The fifth voltage is lower than the fourth voltage.

An embodiment provides a program method used for operating a memory. Thememory includes a first portion and a second portion. The first portionincludes a first word line to a kth word line from bottom to top. Thesecond portion is formed above the first portion and includes a (k+1)thword line to an mth word line from bottom to top. The program methodincludes applying a first voltage to the to the first word line to an(x−2)th word line when an xth word line is used to perform a programoperation; applying a second voltage to an (x−1)th word line; andapplying a third voltage to an (x+1)th word line.

An embodiment provides a program method used for operating a memory. Thememory includes a first portion and a second portion formed below thefirst portion. The first portion includes an (m+1)th word line to an nthword line from bottom to top. The second portion includes a (k+1)th wordline to an mth word line from bottom to top. The program method includesapplying a first voltage to an (x+2)th word line to the nth word linewhen an xth word line is used to perform a program operation; applying asecond voltage to an (x+1)th word line; applying a third voltage to an(x−1)th word line; applying a fourth voltage to the (m+1)th word line toan (x−2)th word line; and applying a fifth voltage to the (k+1)th wordline to the mth word line. x, k and m are integers. The fifth voltage islower than the fourth voltage.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a memory according to an embodiment.

FIG. 2 illustrates the memory of FIG. 1 operated in another condition.

FIG. 3 illustrates a memory according to another embodiment.

FIG. 4 and FIG. 5 illustrate the memory of FIG. 3 operated in otherconditions.

FIG. 6 illustrates a memory according to another embodiment.

FIG. 7 illustrates a memory according to another embodiment.

FIG. 8 illustrates the memory of FIG. 7 operated in another condition.

FIG. 9 illustrates a memory according to another embodiment.

FIG. 10 illustrates the memory of FIG. 9 operated in another condition.

FIG. 11 illustrates a memory according to another embodiment.

FIG. 12 illustrates a flowchart of an program method according to anembodiment

FIG. 13 illustrates a flowchart of an program method according toanother embodiment

DETAILED DESCRIPTION

FIG. 1 illustrates a memory 100 according to an embodiment. The memory100 may include a first portion 110, a second portion 120 and acontroller 190. The first portion 110 may include a first word line WL1to a kth word line WLk from bottom to top. The second portion 120 may beformed above the first portion 110 and includes a (k+1)th word lineWL(k+1) to an mth word line WLm from bottom to top.

In the text, when a word line is said to be programmed, it may mean theword line is used to performed a program operation. A program operationsaid in the text may be an operation for programming a memory cellformed using, for example, a set of transistors.

When an xth word line WLx is used to performed a program operation, thecontroller 190 may apply a program voltage Vpgm to the xth word lineWLx; the controller 190 may apply a first voltage V1 to the first wordline WL1 to an (x−2)th word line WL(x−2); the controller 190 may apply asecond voltage V2 to an (x−1)th word line WL(x−1); and the controller190 may apply third voltage V3 is applied to an (x+1)th word lineWL(x+1). x, k and m are positive integers, 1<k<m and 3≤x.

As shown in FIG. 1, the controller 190 may apply a fourth voltage V4 toan (x+2)th word line WL(x+2) to the mth word line WLm when the xth wordline WLx is used to performed the program operation, and x<m−1.

In FIG. 1, the xth word line WLx is located in the first portion 110 asan example; however, the xth word line WLx may be located in the secondportion 120 in another condition.

FIG. 2 illustrates the memory 100 of FIG. 1 operated in anothercondition. In FIG. 2, the xth word line WLx is located in the secondportion 120. Regarding voltages applied, FIG. 2 may be similar to FIG.1, and it is not repeatedly described.

FIG. 1 and FIG. 2 are merely examples, and each of the word linesWL(x−2), WL(x−1), WL(x+1) and WL(x+2) mentioned above is allowed to belocated in the first portion 110 or the second portion 120.

Regarding the memory 100, the first voltage V1 may have a first level ifthe xth word line WLx is in the first portion 110 and a second level ifthe xth word line WLx is in the second portion 120, where the firstlevel may be lower than the second level. For example, the first voltageV1 in FIG. 1 may have a lower value than the first voltage V1 in FIG. 2.

FIG. 3 illustrates a memory 300 according to another embodiment.Regarding the memories 100 and 300, the memory 300 may include a thirdportion 130 in addition to the first portion 110 and the second portion120.

The third portion 130 may be formed above the second portion 120 andincludes an (m+1)th word line WL(m+1) to an nth word line WLn frombottom to top. As shown in FIG. 3, the controller 190 may apply a fourthvoltage V4 to the (x+2)th word line WL(x+2) to the nth word line WLnwhen the xth word line WLx is used to performed the program operation,m<n, and x<(n−1).

FIG. 4 and FIG. 5 illustrate the memory 300 of FIG. 3 operated in otherconditions. In FIG. 3, the xth word line WLx used to performed a programoperation is in the first portion 110. In FIG. 4 and FIG. 5, the xthword line WLx is in the second portion 120 and the third portion 130respectively.

FIG. 3 to FIG. 5 are merely examples, and each of the word linesWL(x−2), WL(x−1), WL(x+1) and WL(x+2) mentioned above is allowed to belocated in the first portion 110, the second portion 120 or thirdportion 130.

Regarding the memory 300, the first voltage V1 may have a first level ifthe xth word line WLx is in the first portion 110, a second level if thexth word line WLx is in the second portion 120, and a third level if thexth word line WLx is in the third portion 130, where the first level maybe lower than the second level, and the second level may be lower thanthe third level. For example, the first voltage V1 in FIG. 3 may have alower value than the first voltage V1 in FIG. 4, and the first voltageV1 in FIG. 4 may have a lower value than the first voltage V1 in FIG. 5.

FIG. 6 illustrates a memory 600 according to another embodiment. Thememory 600 may be similar to the memory 100 of FIG. 1 and FIG. 2.However, the structure of FIG. 1 and FIG. 2 may include merely one deck,and the memory 600 may have a structure of two decks. In other word, thememory 100 may have a one-deck structure, and the memory 600 may have atwo-deck structure. As shown in FIG. 6, the first portion 110 is of adeck DECK1, and the second portion 120 is of a deck DECK2. The two decksDECK1 and DECK2 may be separated by a joint oxide layer OL. The memory600 may include a lower dummy word line DL, an upper dummy word line DUand the joint oxide layer OL. The lower dummy word line DL may be formedabove the first portion 110. The upper dummy word line DU may be formedbelow the second portion 120. The joint oxide layer OL may be formedbetween the lower dummy word line DL and the upper dummy word line DU.The voltages applied to a one-deck structure may be like the voltagesapplied to a two-deck structure according to embodiments. For example,the voltages applied to the word lines of the memory 600 may be like thevoltages applied to the word lines of the memory 100 of FIG. 1 and FIG.2, and it is not repeatedly described.

FIG. 7 and FIG. 8 illustrate a memory 700 operated in two conditionsaccording to another embodiment. The memory 700 may include a firstportion 710, a second portion 720 and a controller 190. The firstportion 710 may include an (m+1)th word line WL(m+1) to an nth word lineWLn from bottom to top. The second portion 720 may be formed below thefirst portion 710 and include a (k+1)th word line WL(k+1) to an mth wordline WLm from bottom to top.

When an xth word line is used to performed a program operation, thecontroller 190 may apply a first voltage V71 to an (x+2)th word lineWL(x+2) to the nth word line WLn; the controller 190 may apply a secondvoltage V72 to an (x+1)th word line WL(x+1); and the controller 190 mayapply a third voltage V73 to an (x−1)th word line WL(x−1).

If the word line WLx is located in the second portion 720 as shown inFIG. 7, when the xth word line is used to performed the programoperation, the controller 190 may apply a fifth voltage V75 to the(k+1)th word line WL(k+1) to an (x−2)th word line WL(x−2). In FIG. 7, x,k and m are integers, (k+2)<x<(m+1). The condition of FIG. 7 may besubstantially similar to the condition of FIG. 1; however, FIG. 7 isprovided to introduce FIG. 8 to FIG. 11.

If the word line WLx used to performed a program operation is located inthe first portion 710 as shown in FIG. 8, the first voltage V71, thesecond voltage V72 and the third voltage V73 may be applied by thecontroller 190 as shown in FIG. 7; however, the controller 190 may applya fourth voltage V74 to the (m+1)th word line WL(m+1) to an (x−2)th wordline WL(x−2). The controller 190 may apply the fifth voltage V75 to the(k+1)th word line WL(k+1) to the mth word line WLm. In FIG. 8, x, k andm are integers, 0≤k<m, (m+2)<x<(n−1). The fifth voltage V75 may be lowerthan the fourth voltage V74.

According to another embodiment, as shown in FIG. 6, the first portion710 and the second portion 720 shown in FIG. 7 and FIG. 8 may be of twodecks respectively, and the two decks may be separated by a joint oxidelayer. As shown in FIG. 6, the two decks may have an upper dummy wordline and a lower dummy word line respectively.

FIG. 9 illustrates a memory 900 according to another embodiment. FIG. 10illustrates the memory 900 of FIG. 9 operated in another condition.

As shown in FIG. 9, the memory 900 may have three portions 910, 920 and930. The first portion 910 and the second portion 920 may be similar tothe portions 710 and 720 shown in FIG. 7. The third portion 930 may beformed above the first portion 910 and include a plurality of word linesWL(n+1) to WLq from bottom to top. The condition of FIG. 9 may besimilar to FIG. 7 where the word line WLx used to performed a programoperation is located in the lowermost portion 920. The controller 190may apply the first voltage V71 to the plurality of word lines WL(n+1)to WLq of FIG. 9. The variable q is an integer, and q>(n+1).

The memory 900 of FIG. 10 may have the same structure as shown in FIG.9. The condition of FIG. 10 may be similar to FIG. 8 where the word lineWLx used to performed a program operation is located in the portion 910above the lowermost portion 920. The voltages applied to the portions910 and 920 may be like the voltages applied to the portions 710 and 720of FIG. 8. As shown in FIG. 9, the controller 190 may apply the firstvoltage V71 to the plurality of word lines WL(n+1) to WLq of the portion930.

FIG. 11 illustrates a memory 1100 according to another embodiment. Thefirst portion 1110 and the second portion 1120 of the memory 1100 may belike the portions 710 and 720 of FIG. 8, and the memory 1100 may furtherinclude a third portion 1130 formed below the second portion 1120.Similarly, the xth word line WLx may be used to perform a programoperation. Hence, the memory 1100 may include three portions and have astructure like the memory 900 of FIG. 9 and FIG. 10. As shown in FIG.11, the third portion 1130 may include a first word line WL1 to a kthword line WLk from bottom to top. The controller 190 may apply a sixvoltage V76 to the first word line WL1 to the kth word line WLk. 0<k,and the sixth voltage V76 is lower than the fifth voltage V75.

Although the numberings of the portions and word lines are not the same,the memories 900 and 1100 shown in FIG. 9 to FIG. 11 may be regarded asa same memory operated in different conditions.

In FIG. 9, the word line (e.g., WLx) used to performed a programoperation is located in a lowermost portion of the three portions.

In FIG. 10, the word line (e.g., WLx) used to performed a programoperation is located in a second lowermost portion of the threeportions.

In FIG. 11, the word line (e.g., WLx) used to performed a programoperation is located in an uppermost portion of the three portions.

As shown in FIG. 9 to FIG. 11, when the word line WLx used to performeda program operation is located in the different portions, differentvoltages may be applied to the word lines below the word line WLxaccording to the corresponding portion(s).

In the example of FIG. 9 to FIG. 11, the relationship among voltages maybe V76<V75<V74. In other words, a same voltage may be applied to wordlines of a same portion located below the portion corresponding to theword line (e.g., WLx) used to performed a program operation, and a lowervoltage may be applied to word lines of a portion located lower.

FIG. 12 illustrates a flowchart of a program method 1200 according to anembodiment. The program method 1200 may be used to operate the memory100 of FIG. 1 and FIG. 2 and the memory 300 of FIG. 3 to FIG. 5. Themethod 1200 may include following steps.

Step 1210: apply a first voltage V1 to the to the first word line WL1 toan (x−2)th word line WL(x−2) when an xth word line WLx is used toperform a program operation;

Step 1220: apply a second voltage V2 to an (x−1)th word line WL(x−1);and

Step 1230: apply a third voltage V3 to an (x+1)th word line WL(x+1).

Step 1210 to Step 1230 may be performed when the xth word line WLx isused to perform the program operation. In addition, when the xth wordline WLx is used to perform the program operation, a fourth voltage V4may be applied as show in FIG. 1 to FIG. 5 and as described above. Therelationships among the voltages (e.g. V1, V2, V3 and V4) shown in FIG.1 to FIG. 5 may be as described above.

FIG. 13 illustrates a flowchart of a program method 1300 according to anembodiment. The program method 1300 may be used to operate the memory700 of FIG. 8, the memory 900 of FIG. 9 and FIG. 10, and the memory 1100of FIG. 11. The method 1300 may include the following steps.

Step 1310: apply a first voltage V71 to an (x+2)th word line WL(x+2) tothe nth word line WLn when an xth word line WLx is used to perform aprogram operation;

Step 1320: apply a second voltage V72 to an (x+1)th word line WL(x+1);

Step 1330: apply a third voltage V73 to an (x−1)th word line WL(x−1);

Step 1340: apply a fourth voltage V74 to the (m+1)th word line WL(m+1)to an (x−2)th word line WL(x−2); and

Step 1350: apply a fifth voltage V75 to the (k+1)th word line WL(k+1) tothe mth word line WLm.

Step 1310 to Step 1350 may be performed when the xth word line WLx isused to perform the program operation. In addition, when the xth wordline WLx is used to perform the program operation, a six voltage V76 maybe applied as shown in FIG. 11 and as described above. The relationshipsamong the voltages (e.g., V71, V72, V73, V74, V75 and V76) shown in FIG.7 to FIG. 11 may be as described above.

In summary, by using a memory sectioned to have a plurality of portionsand applying voltages to the word lines of the memory according to theportions, program disturbance and pass voltage disturbance may bereduced according to simulations and experiments. In addition, by usinga same voltage source to apply a voltage to word lines of a same portionor word lines of different portions, less voltage sources may berequired, and the area of system may be smaller. Hence, problems of thefield can be reduced.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

1. A memory comprising: a first portion comprising a first word line to a kth word line from bottom to top; and a second portion formed above the first portion and comprising a (k+1)th word line to an mth word line from bottom to top; and a controller configured to apply a first voltage to the first word line to an (x−2)th word line, a second voltage to an (x−1)th word line, and a third voltage to an (x+1)th word line when an xth word line is used to perform a program operation; wherein x, k and m are positive integers, 1<k<m and 3≤x.
 2. The memory of claim 1, wherein the controller is further configured to apply a fourth voltage to an (x+2)th word line to the mth word line when the xth word line is used to perform the program operation, and x<(m−1).
 3. The memory of claim 1, further comprising a third portion formed above the second portion and comprising an (m+1)th word line to an nth word line from bottom to top wherein the controller is further configured to apply a fourth voltage to the (x+2)th word line to the nth word line when the xth word line is used to perform the program operation, m<n, and x<(n−1).
 4. The memory of claim 3, wherein: the first voltage has a first level if the xth word line is in the first portion; the first voltage has a second level if the xth word line is in the second portion; the first voltage has a third level if the xth word line is in the third portion; and the first level is lower than the second level, and the second level is lower than the third level.
 5. The memory of claim 1, wherein: the first voltage has a first level if the xth word line is in the first portion; the first voltage has a second level if the xth word line is in the second portion; and the first level is lower than the second level.
 6. The memory of claim 1, further comprising: a lower dummy word line formed above the first portion; an upper dummy word line formed below the second portion; a joint oxide layer formed between the lower dummy word line and the upper dummy word line; wherein the memory has a two-deck structure. 7-20. (canceled) 